Self-heating container



Dec. 9, 1952 E. J. RlvocHE ET AL 2,620,788

SELF-HEATING CONTAINER Filed Nov. 5, 1950 3 Sheets-Sheet l /9 @wwQQQQQQ@ 27 @QQ/9@ I @QQ/99@ Q EUGENE J- 11, N n l b l H N ,f mwATTORNEYS Dec. 9, 1952 Filed Nov. 5, 1950 E. J. RlvocHE ET AL 2,620,788

SELF-HEATING CONTAINER 3 SheeLS-Sheetl 2 Dec. 9, 1952 E. J. RlvocHE ETAL 2,620,788

SELF-HEATING CONTAINER Filed NOV. 5, 1950 5 Sheets-Sheet 5 INVENTORS G.u@ Rn/@CHE F1 9 E fgwv ATTORNEYS Patented Dec. 9, 1952 SELF-HEATINGCONTAINER Eugene J. Rivoche and Lev Sukacev, Washington, D. C.

Application November 3, 1950, Serial No. 193,868

36 Claims. l

This invention relates to self-heating containers for the packaging offoods or other materials which it may be desired to heat withoutrecourse to extraneous heating agents. Such containers are particularlyadapted for emergency use by the Armed Forces and others underconditions where it is impossible or impractical to prepare hot foodsunder the usual conditions.

The self-heating containers of the present invention embody improvementson the type of self-heating container disclosed in the application filedby Lev Sukacev on June 28, 1950, Serial No, 170,757. In that applicationthere is disclosed and claimed a self-heating container in which thecontainer for the foods which it is desired to heat is mounted fortelescopic movement in an outer supplemental container, and lime orother material, which on reaction with water liberates heat and in doingso expands in volume, is interposed between the bottom of the foodcontainer and the outer supplemental container. The telescopic mountingof the food container within the outer container permits expansion ofthe lime when water is added without subjecting either container toexcessive pressure, and thereby makes it possible to construct bothcontainers of relatively light-weight material.

An important consideration in any self-heating container is theeiiiciency of the transfer ol" heat from the exothermic material to thefood container, particularly if the container may be used in coldclimates where the heat necessary to bring the food to the desiredtemperature is greater, and where dissipation of liberated heat may begreater than otherwise.

As the amount of exothermic material needed to bring the food of thecontainer to the desired temperature is vinversely proportional to theefliciency of heat transfer thereto from the exothermic material, a highheat transfer eiciency permits the use of less of the exothermicmaterial, as well as making it possible to use a smaller container, animportant factor where transportation space is of importance.

When water is added to burnt lime, the resulting exothermic reaction, orslaking, causes the body of lime to swell or expand, if unrestrained, toapproximately three times its original size. The expanding or swellingof the lime reduces the heat conductivity thereof by as much as 90 to95%.

When the exothermic material is lime or other material which expandsappreciably whenv Cil water is added to it, some expansion is desirablein order that it shall not be necessary to use materials for thecontainer which will be strong enough to resist the entire pressuredeveloped by the expanding exothermic material. but unlimited expansionis not desirable since it too greatly reduces conduction of heat to thefood container. Consequently, one of the features of the presentinvention is to provide a self-heating container of the type disclosedin the aforesaid application in which the food container has only alimited outward movement relative to the outer container, with theoutward movement being stopped when the slaking lime has expanded tofrom about one and onehalf to two and one-half times its originalvolume, and before it has reached its normal unrestrained expansion.Adv'antageously, the outward movement of the food container may bestopped when the lime has expanded to about twice its original volume.By thus permitting a partial expansion only of the lime, the lime willbe maintained in a somewhat compressed, more dense state, and its heatconductivity will be much greater than that of the lime in itsfully-expanded state. Also, as the bottom of the food container is therestraining force on the expanding lime, the lime will cause a goodheat-conductive contact to be made with the food container, which alsoenhances the conduction of heat from the lime to that container. Thefact that neither the food container nor the outer supplementalcontainer has to resist the full expansive force of the lime permits theuse of relatively light material for construction of both of thosecontainers, and thereby lessens the cost of the self-heating container.The present invention further provides for increased conduction of heatfrom the exothermic material to the food container by providing metal,or other elements of good heat-conducting properties which, throughoutall stages of expansion of the lime, are maintained in contact with thebody of lime and the food container and act as conductive paths fortransferring heat from the hot lime to the food container.

The dissipation of heat from the exothermic material, other than to thefood container to be heated, is prevented, or largely retarded, bysuitable insulating means, and by enclosing the entire self-heatingcontainer in an enclosingpcasing of cardboard or other material LhavingrelativelyA good insulating properties which insulates it from thesurrounding atmosphere and also prevents air-currents from picking upheat both from the food container and the outer supplemental container.

Whereas the self-heating container of the foresaid application includeda receptacle for water to be added to the exothermic material, thecontainer of the present invention is packaged dry, that is, withoutWater to be added to the exothermic material, and special means areprovided to facilitate the addition of Water and also to assure that theproper amount of water to liberate the maximum heat from the exothermicmaterial is added.

Other features of the invention will be clear from the following moredetailed description taken in connection with the accompanying drawings.However, it is to be understood that such further description is by. Wayof exemplication and the invention is not limited thereby, except to theextent set forth in the appended claims.

In the drawings:

Fig. 1 is a vertical cross-sectional viewv o f a self-heating containerembodying the invention.

and enclosed. in an insulating casing,

Fig. 2 is a View similar to,y Fig. 1 showing the relative position ofthe partsafter the exothermic material has expanded on reaction withwater,

Fig. 3 is a vertical sectionalI view of the lower portionv of theself-heating container removed from its insulating casing and showingthe manner in which water is retained on the bottom ofthe outersupplemental containerfor; passage to the exothermic material,

Fig. 4 is a horizontal cross-sectional. view, partly broken away, online 3.--3v of Fig. 1,

Fig. 5 is a perspective view, with parts broken away, of one of theexpansible containers for the exothermic material,

Fig. 6. is a vertical cross-sectional view of a modified form of aself-heating container embodying the invention, with the` insulatingAcasing removed, g

Fig. 7 is. a horizontal cross-sectional View on line 1 1 of Fig. 6,

Fig. 8 is a vertical cross-sectional view. of a self-heating containerhaving a space| withiny the outer confines ofthel food container forthez exothermic material, also shown withv theA outer insulating casingremoved, and

Fig. 9 is a vertical cross-sectionalz view ofa self-heating containerembodying the invention and particularly adapted for the thawing andheating of frozen foods, removed from itsouter insulating container.

Referring now tol the drawings, and. first to the form of the inventionshown in Figs. 1 to 5, the material which isA packed for subsequentheating, hereinafter referred to. as food but which may be, material oflany kind, ishermetically sealed in, a, container I of metal or othermaterial having good heat conductivity, in a,

manner well-known, in the food packaging art. Such containers may betheI usual tinned. or lacquered metal, cans.

The food container l is mounted for subsequent telescopic movement in anouter, openended supplemental' container 2, of' the same shape as thecontainer I and having a, bottom 3 and side wallsv 4. The food containerI and the supplemental. container 2, may be of any desired shape andproportions, although normally, a round, relatively flat foodcontaineris preferred. When the food container has relatively littleheight, the heating of the food therein, in the manner set forth below,as facilitated.

The side walls 4 of the outer container have an inside diametersufiiciently larger than the outside diameter of the food container tojust compensate for the increased diameter caused by the crimped seal 5at the periphery of the bottom of the food container. Thus, while thefood container may move freely within the outer container, the crimpedseal 5 lies sufficiently close to the outer container to effectivelyprevent any appreciable amount of the exothermic material being forcedpast it.

After the food container has been placed in the outer container 2, theouter free edge of the side walls 4 are bent or curled inwardly toprovide an internally-extending flange or projection 6 to form a stop.which on outward movement of the food container is engaged by thecrimped seal 5 and thereby limits the outward movement of the foodcontainer.

If the food is not packaged in a container having an outwardly-extendingcrimped seal which can engage the inwardly-extending ange. or projection6, a suitable outwardly-extending ange or projection should be formedon, the lower portion of the food, container. Such a projection may bein the form of an annular ridge formed by grooving from the inside, asinv a modification to be described later.l or spaced projections formedby indenting from the inside.

For the purpose of heating the food Within the container I, exothermicmaterial 1, that is, a material which will react with water toliberateheat, is placed between the bottom of the food container I and thebottom` of the outer supplemental container. The exothermic ma.- terialmay be of any knownmaterial or composition which will react with waterto liberate a substantial amount of heat. but we prefer burnt lime as itis readily available, is` cheap, andon reacting with water liberateslarge amounts of heat.

The exothermic material 1 is placed in sectorshaped receptacles 8 ofaluminum or-other metal having good heat-conductiveproperties; Four suchcontainers are used but a lesser or greater number may be used ifdesired. If the food container is quite large, six or even eight. ormore such containers may be used. Each of the sector-shaped receptaclescomprises a lowerv tray portion 9 and a cover portionl0 havingdownwardly-extending side` anges II and I-2which make a sufficientlygood contact with the upwardly-extending sidesl I3 ofthe lower trav,vportion to readily conduct heat from the trayK p01'.-

tion to the topof the cover portion. However..

the frictional engagement of the flanges of the cover portion with theside walls of the tray portion is no t such aswill prevent relativemovement of the cover and tray portions on expansion of the exothermicmaterial when` reacted4 with water.

The cover portion of each4 of the receptacles for the exothermicmaterial' is contoured to ac,- curately conformto the contour of thatportion of the bottom of the food receptacle withwhichit is in contact,so that the: bottom of the-l food container will lie in close,heat-conductive contact with the top of the several receptacles for theexothermic material. When the bottom ofthe food receptacle is reinforcedwith annular. outwardly-extending grooves or ribs, the severalIreceptacles 8 will haveY aligned' arcuate grooves 5 complementary tosuch grooves or ribs of the food container.

The top of the cover portions I lpreferably are solid to provide acontinuous heat-conduct- `ing surface to the bottom of the foodcontainer, although, if desired, one or more openings may be placed inthe top of the cover portion to permit direct conta-ct by the lime inthe receptacles with the bottom of the food container.

To permit access of the water to the exothermic material. as describedlater, the bottom of the tray portions are perforated as at I4. Theperforations -advantageously are so arranged that continuous straightmetallic vpaths for the conduction of heat are provided both to thestraight radial walls and to the arcuate outer wall of the trayportions. The perforations advantageously are formed by a punchingoperation which will leave inwardly-extending flanges or burrs I at thesides of the perforations. Such flanges or bur-rs when the exothermicmaterial .is reacted with water, will assist in tr-ansferring heat fromthe body of the exothermic material to the metal walls of the lower trayportions.

The straight radial side walls and the outer arcuate walls of the coverportions I 0 are of a depth suilcient to extend below the bottom of the-lower tray porti-on 9, the depth of the outer arcuate Wall is greaterthan the straight radial side walls, and to accommodate such additionaldepth the periphery of the bottom of the outer supplement-al container 2is grooved outwardly as at I6 to provide a trough into which the arcuateouter wall of the cover is received.

The depth of the flanges I I and I2 is such that when the exothermicmaterial has expanded and moved the cover members IU relative to thetray porti-ons 9 the maximum amount permitted by the limiting flange 6,they still will contact the side walls of the tray portions S andprovide a good conductive path for the conduction of heat from theexothermic material to the top of the covers and to the bottom of thefood container.

In the drawings the flanges of the covers are shown as making a closefitting contact with the outside of the side walls of the tray portions.If desired, the flanges of the covers can be received within and make aclose fitting contact with the inside of the side walls of the trayportions.

To further assist in the transfer of heat from the internal portions ofthe body of reacting exothermic material to the top of the receptacles 8and from them to the bottom of the food container, a mass of metalshavings or other flexible springy material I1 of high heatconductivity, such as shavings of aluminum, copper, etc., are embeddedin the exothermi-c material in each of the receptacles 8. These shavingsnormally are in the form of a springy mass several times the depth ofthe receptacle 8 so that when the covers I0 are placed on the trayportions and pushed tothe position shown in Fig. 1, the mass of shavingswill be compressed. As the receptacles eX- pand under the expansiveforce of the reactingr exothermi-c material, the springy mass ofshavings II will open up and maintain contact with the covers I0 andform a metallic path for good conduction of heat from the mass ofexpanded exothermic material to the covers I0 of the receptacles, fromwhich the heat is conducted to the bottom of the food container.

Instead of using a springy mass of metal shavings or the like to conductheat from the mass of exothermic material to the covers of thereceptacles, springs, or flexible members secured to the covers I0 andextending down into the mass of yexothermic material, as disclosed inother embodiments of the invention to be described, may be used.

A layer I8 'of exothermic material of the order of one-tenth inch inthickness is interposed between the bottom of the sector-shapedreceptacles 8 and the bottom of the outer container 2 and serves toinsulate the receptacles 8 from the container 2 and thereby prevents orgreatly retards the passage of heat from the receptacles 8 to the outercontainer. The .layer I8 also serves to maintain the lower edges of theflanges I I and I2 of the cover portion spaced from the bottom of the:outer container so that they Will not provide a path -for theconduction of heat from the receptacles 8 to the outer container. Tofurther insulate the receptacles 8 from the outer container and therebyfurther reduce loss of heat, rings I9 of suitable insulating materialare interposed -between the arcuate flanges I2 of the severalreceptacles 8 and the side wall of the outer container.

The exothermic .material normally is maintained hermetically sealedbetween the food receptacle and the -outer container 2 by a sealing band20 extending around the side walls of the food container and overlyingthe upper end of the side Walls of the outer container 2. The sealingband may be an adhesive tape, a strip of plastic, or rubberized, orother appropriate material. The sealing band 20, while adequate tohermetically seal the container, is sufficiently weak to rupture underthe expanding force of the ex-othermic material sh-ould its removal beoverlooked before the container is put into use. If desired, a metaltape, wire, or band 2I may be wound about the food container and theouter container from top to bottom to give protection against removal ofthe food container from the outer `container until heating of thematerial in the food container is desired.

Water is admitted to the exothermic material in the receptacles 8 bypunching holes in the bottom of the outer container 2 thro-ugh which itpasses. To facilitate the punching of such holes, the bottoms of thereceptacles 8 are formed with a series of slight indentations 22. As theselfheating containers are designed primarily for emergency use, or foruse where punching tools may not readily be accessible, a nail or otherpunching tool may be packed in the container for use in making the punchholes for the entry of water.

A gauge ring 23 is mounted about ythe lower portion of the outerco-ntainer 2 and has its inner end 2li turned inwardly to form aninwardly-k extending flange which makes a frictional sliding fit withthe side walls of the outer container. Outward movement of the gaugering is limited by engagement of the inwardly-extending flange 24 withan outwardly-extending projection 25 adjacent the bottom of the outercontainer. The width of the gauge ring 23 is such that when the ring ismoved outward to its maximum extent, and the container inverted, thering will define a space having a volume equal to the volume of waterwhich should be added to the exothermic material to give the maximumheating eifect.

To further prevent dissipation of heat when the container is being used,it is completely enclosed in an outer casing 26 of cardboard, insulatingboard, or the like. The casing 26 comprises a lower receptacle 21 and acover 28 having a depending side wall 29 of suflicient depth tomainasogrss tain: contact with the side wall of the lower.' receptacleYwhen the foodicontainer'has been raised to the maximum amount permittedby the. limit.- ing ilange 6 under the expansive force exerted by theexothermic material., A sealing strip 20x, similar to .the band 20, maynormally secure the cover. 28 in place on the. receptacle 21'..

When the container is. to he used, it is; removed from. the casing 26and. the retaining band 2l and the. sealing strip; 20x.- are. removed.Thecontainerthenis temporarily inverted, holes punched in the bottom. ofthe outer receptacle.y for the passage of water toV the exothermicAmaterial, and thev gauge ring 23 lifted to the position shown in Fig. 3.The space enclosed by the gauge rimar 23 is: then filledA with water andthe. container left inverteduntil all of the water has passed throughtheV punch holes in the. bottom of the outer container and into theexothermic material. The

container then is .turned back to its. normal pOstion. with theexothermi'c material at the bottom so that the heat will rise upwardlytherefrom in a normal manner and be conducted by the metall-icconductive path heretofore described to. the food' container. The foodcontainer is then opened before its 'becomes too hot, and to permitoccasional stirring ofthe food during the heating operation tofacilitate4 transfer of heat to all portions thereof, and is replaced intheouter casing 26 and retained thereinuntil` the food in the foodcontainer is. thoroughly heated..

The. exothermic material on'. reaction with water puffs or expands; In.the case of burnt lime, the expansion if unrestrained would result inthe lime being increased .to approximately three. times its originalvolume, with a reduction of its normally low heat conductivity by about90 to. 95%. After thel lime has expanded to approximately two timesl itsoriginal volume, the food container will have been lifted to an extentsuch that the bottom crimped seal 5 engages the inwardly-extending ange6 of the outer container and further outward movement of the foodcontainer is prevented. However, the generation of gas continues andcreatesy an internal pressure. within the receptacles 8 which forcestheir covers IU tightly against the bottom of the food container so thata good heat-conductive contact is made.

The engagement of the crimped seal 5 with the flange 6 also takes placebefore the side flanges l I and l2 are separated from contact with theupwardly-extending side walls of the tray portions 9. Thus, thecontacting side walls of the tray and cover portions of the receptaclesalso provide a good heat-conductive path to the top of the covers incontact with the bottom of thev food container.

As the heat conductivity of the lime progressively decreases onexpansion of the lime, the controlling of theextent of the expansion ofthe lime to less than its normally free expansion also makes the limeitself a better conductor for transferring heat to thev covers and fromthem to the food containers.

As the lime expands and separates the cover and tra-y portions ofthereceptacles 8,Y the mass of metal shavings I'I which have beenmaintained under compression during the shipping and storage of thecontainer expands and continues to maintain contact with theundersurface of the cover portions IU and formpaths for good conductionof heat from the interior parts of the lime in each receptacle. Theexpansion of the limeY also tends to some exten-t toy expand the mass ofmetal shavings and to cause them to maintain. a goodv heat-conductivecontact with the cover portions of the receptacles. H.

The form of self-heatingV containershown in Figsdl and'I Z generally isthe same as that dis.- closed; in Figs. 1. to 5 and; comprises a foodcontainer 3U, and an. outer. supplemental container 3| having` a. bottom32 and' sidewalls 33, the outer ends, of. which are curled inwardly toprovide. a. flange 34 which,I on. expansion-.of the exothermic material,is. engaged by an outwardly-extending bulge: 35. at the peripheryof thelower portion of the. foodcontainer to limit. further outward move.-ment of that container under the. expansive force of. theV exothermicmaterial'.

The sector-shaped, receptacles 36 for the lime or other exothermic'material are generally similar to.A those of the preceding iiguresandcomprise tray portions 31 having side anges 38perforated bottoms 3.9,and cover portions 40 having soli-d tops 4l.- .and'depending sidevflanges 42 which have a close lit with and extend below the. side wallsof the. tray portion. Asin the preceding figures, the arcuate outer sideflanges of thev covers, which .are of greater depth than the radial sidewalls. of the; tray portions, are. received in an annular groove ortrough 4-3 at the periphery of the bottom of the outer container.However, in this embodiment of the invention the radial side walls ofthe. trays and the coverportions do not extend quite to the center ofthe container and do not meet one another. With this arrangement,4 acen-tralspace 44 is'provided at the. apex oieach of the. sector-shapedreceptacles into which water may enter and from which it may passv to.the several. receptacles' through the openings at` their several apices.

This form of the invention is adapted for use with foodv containerswhich have a concave bot'- tom, and the several receptacles 36 are.curved so that. at least their cover portions. accurately conform to thecurvature of the. bottom ofthe food container so. as to make goodheat-conductive. contact therewith. The receptacles 36` also areinsulated from the. outer container by an insulated layerv ofi lime orother exothermicv ma-` terial 45', and a ring 45" of insulatingymaterial isv interposed between thel outer flange of the cover portions.40 and the o uter container tov prevent transfer of heat when thecontainer is put into operation. .f

The depth of the. groove or trough 43 is sutilcient. that', withthevconcave bottom 32 of the outer container, it provides.A a space.adequate, when the container is. inverted, to contain sufl`- cientAwater to properly activate the exothermic material in the receptacles36.

The concave bottom 32v of the outer container is provided with slightindentations to facilitate punching.

Instead of a sealing bandoverlapping the topV edge of the outercontainer 3l and being secured to.- the sidewalls of the food container,like the band 2u previously described, the exothermic material in thereceptacles 3S is hermetically sealed* by a.v metallic cover 48 for theouter container 3f having aside flange 41. suiciently wide that whenthe, cover i's placed over the outer container with the. fcod containerin it, it. will overlap the side walls; of the outer container. Hermeticsealing is obtained by soldering the lower edge of the nange 41 to theside Wall of the outer container with a solder which is suiciently weakto rupture.` under the expansive force of the exothermic material shouldthe cover 46 not. be removed before the, container is put intooperation.

Instead of embedding metal shavings in the body of the exothermicmaterial placed in the receptacles to transfer heat from the body of theexpanded exothermic material to the covers of the receptacles 36,' eachreceptacle contains a spring member 48 having a flat top section 49lying in close heat-conductive contact with the top of the receptacle,and a plurality of radiallyextending legs 50 and 50.

In order that the legs will extend to `different parts of the body ofthe exothermic material for the purpose of conducting heat therefrom tothe flat top section, the legs 50 extend radially outwardly, while thelegs 50' extend radially inwardly from the periphery of the central fiat-top section 49. When the receptacles are closed with the springs inthem, the tops of the receptacles exert a pressure on the legs whichspreads the legs 50 outwardly and the legs 50 inwardly, as shown inFigs. 6 and 7. When the exothermic material expands and lifts the coverportions 40 of the receptacles 36 and the food container, the legs 50and 5U', which were under compression, raise the covers 49 and maintainthem in tight heat-conductive contact with the bottom of the foodcontainer. The legs U and 50 of the spring member conduct heat from them-ass of the exothermic material to the central flat top section 49 fromwhich it is conducted to the top of the receptacles 36 and by them tothe bottom of the food container.

The self-heating containers of this form of the invention will beenclosed in an insulating casing, the same as the container ofthe'preceding figures; and otherwise are the same and put into operationin the same manner as the container of that embodiment of the invention.

Fig. 8 illustrates a somewhat simplified design of lthe self-heatingcontainer. In this embodiment of the invention, the metallic foodreceptacle 52 has its bottom formed with a dome-like portion 53 whichextends into the food container a distance equal approximately toone-half its height. The food container is completely enclosed andhermetically sealed within an outer supplementary container 54. The topof the outer container is removably connected to the body portionthereof by a sealing strip 56 which may be wound onto a suitable keywhen the cover is to be removed. Such means for hermetic-ally sealingmetal containers are well known in the packaging art and are usedextensively in the hermetio sealing of packaged coifee.

The side walls of the outer container are provided with aninwardly-extending peripheral groove or circumferentially spacedindentations 51 for engagement by the crimped sealing flange 58 attheperiphery of the bottom of the food container to limit outwardmovement of the food container.

The space within the dome-like portion 53 and the space between thebottom of the food container 52 and the bottom of the outer container 54is filled with burnt lime or other exothermic material which will reactwith water with resultant expansion and liberation of heat.

As in the previously-described embodiments of the invention, the bottomof the outer receptacle is provided with slight indentations 59 tofacilitate the punching of holes for the passage of water to theexothermic material when the container is to be put into operation.

The side walls of the outer container 54 extend below the bottom wall ofthat container to provide a circumferential flange 60 of adequate depth10 to define a space just suiiicient to receive an amount of water toproperly activate the exothermic material.

To facilitate the transfer of heat from the interior parts of theexothermic material, metal shavings such as are shown in Figs. 1 to 3,or metal springs, such as are shown in Fig. 6, may be embedded in thebody of exothermic material; or chains or other exible members 6| ofgood heat-conductive material may be soldered to the bottom of the foodcontainer and extend into the body of exothermic material. As the foodcontainer 52 is raised under the expansive force of the exothermicmaterial, such flexible members provide a good heat-conductive path fromthe interior of the body of exothermic material to the bottom of thefood container.

The provision of the dome-like portion 53 brings the source of heat intothe central portion of the food in the food container and therebyenables the food to be heated more quickly, since the heat does not haveto travel as great a distance to the food in the more remote portions ofthe food container; and also because a greater heating surface isprovided for the transfer of heat from the exothermic material to thefood within the food container.

In Fig. 9 we have shown a self-heating container which is particularlyadapted to the thawing and subsequent heating of frozen foods.

In this embodiment of the invention, the con-v struction of the foodcontainer, its outer supplementary container and the receptacles for theexothermic material are the same as the corresponding parts of Figs. 1to 3 except that the gauge ring 23 is omitted at the bottom of thecontainer and the bottom of the outer supplemental container 3a isdished to provide aspace to receive water to activate the exother-micmaterial, and outward movement of the food container is limited by aninwardly-extending circumferential groove 6EL in the side wall of theouter container rather than by an inwardly-extending flange portion atthe top of the side wall of that container. In this embodiment of theinvention, the same reference characters primed are used to designatethose parts which correspond to similar parts of the self-heatingcontainer shown in Figs. 1 to 3.

Frozen foods are very poor conductors of heat. Therefore, when frozenfoods are to be heated, the eiciency of the heating can be greatlyincreased if the heating is done in two stages and. with separate bodiesof the exothermic material; one stage and one body of exothermicmaterial being used to thaw the frozen food, and the second stage andthe second body of exothermic material being used to heat the thawedfood to the desired temperature. To that end, the selfheating containerin this embodiment of the invention includes a supplemental body of theexothermic material 63 contained in a tray or receptacle 64 of aluminumor other good heat-conductive material on top of the food container. Thebottom of the receptacle 64 is shaped to accurately conform to the topof the food container I so that it will have a good heat-conductivecontact therewith.

A springy body of aluminum or other metal shavings lla, or of any of theother forms of heat-conductive means heretofore described, is embeddedin the exothermic material 63 to facilitate the transfer of heat fromthe inner parts of the exothermic material to the bottom of thereceptacle 64 when that body of exothermic material is being used tothaw the frozen food.

amazes A cover 65 fits over the receptacle 64 and hasa depending sidewall which extends .to .adjacent the bottom of the outer container .2'.and .is hermetically sealed thereto .by a sealing strip -66 to preventaccess of moisture of the air to .the exothermic `material .in thereceptacles 8 and 64. The top .of the cover member .65 has slightindentations 61 to facilitate punching to form holes for lthe admissionYof Water to the exothermic material 63 when the heating eifect thereofis to be utilized to thaw the frozen food.

The peripheral edge of the top of the ,cover member 65 is Aprovided withan outwardly-ex tending 'flange 68 which limits outward .movement of .agauge ring 69, which, like vthe gauge ring23 of Figs. 1 to 3, isprovided to denne aspace to receive a supply of water just sumcient toactivate the exothermic material 263. Outward movement of the gauge ring'69 is Ylimited by .an inwardly-extending flange 'ILO at 'its inner endengaging the outwardly-extending flange '6B cf the cover 65.

The entire unit above described is enclosed .in a casing 2E'3L ofcardboardor other insulating .material. The cover of the casing 2lianormally is secured in place by a sealing strip '3911.

When the self-heating container of 'this embodiment of the invention isto .be put into operation, the sealing strip 36a vis removed .and theself-heating unit removed from the .insulating casing 26K. The sealingstrip 66 is then removed. Holes are then punched through .theindentations 61, the gauge ring 69 lifted until the flange 10 at thelower edge thereof engages the ila-nge G8, and the space defined by .thegauge ring .lled with Water. As soon as V.the water has passed throughthe punched holes into thelime or other exothermic material, the unit is.inverted and put back into the casing with Vthe receptacle G4 for theexothermic material `63 at the bottom and permitted to remain thereinuntil all of the 'heat given off by the exothermic material is absorbedby the frozen food.

As the lime or other exothermic material expands on reaction with thewater, the wall ofthe receptacle 64 in contact with the food containerwill be pushed tightly against the food container in goodheat-conductive relation thereto. Also, the expansion of the lime willcause both the food container and the outer supplemental Vcontainer 2 tobe raised with the vcover member '65.

After the frozen food has absorbed the `heat from the exothermicmaterial, the unit is again removed from the casing and the cover member65 and the receptacle .64 both removed and discarded. The exothermicmaterial 4in the receptacls 8' is then activated and the food, nowcompletely thawed, is heatedin the manner previously described inconnection with the embodiment of the invention shown in Figs. 1 to 5.

Ordinarily, means will not be provided .to limit the expansion of theexothermic material 63, since the use of such means might interfere withthe ready removal of the receptacle '64 after the heat of the exothermicmaterial E3 .has been Autilized to thaw the frozen food.

In order to facilitate the inward .turning of the upper edge portions ofthe side walls of .the .outer supplemental containers to ,form the.limiting flanges shown in Figs. Yl, .2 and 6, after the flood containerhas been Iinserted into the outer container, a wire ring H is .droppedinto the space between the side walls .of the food container 'and theouter container to rest upon and be supported by the outwardly extendingvcrimped seal at the lower peripheral edge of the `food container to A12act as an anvil about which the umn' -eugefot the outer -containersmaylbe turned during the iianging operation.

While yall .embodiments of the invention -above described `are drypacks, in that none .of the units is provided with water to activatey.the exothermic material, it is to be understood that, if desired, .theseveral Vforms of the self-.heatingcontainers specically described maybe modified to include a water receptaclesuch as is Idisclosed in thefore-said application.

In `the several forms of the inventiondescribed, the Yheat generated bythe reaction .of the exothermic material with water .is utilized to .themaximum .extent in heating the food, and -dissipation of heat to :the.surrounding atmosphere is maintained at a minimum. Consequently, lessof the exothermic material .is needed to bring the food `toapredetermined temperature, and .the voverall size of the self-heatingcontainers may be smaller lthan otherwise. Also, .the invention.provides .a .self-.heating container in which all of the ex=othem1icmaterial is between the bottom of .the food container and the bottom ofthe outer container, and .good heat-conductive paths are provided VforIconducting lthe heat therefrom .to-the flood in thefood container.

Various changes may be made .in .the .details of 'the construction ofthe various self-heating containers without ,departing from theinvention or sacri'cing the advantagesthereof.

We claim:

l. A self-heating container comprisinganouter container. a foodcontainer of heat-conductive material within the outer container .andtelescopi-cally movable therein, an .exothermic material which onreaction with water liberates heatVJan-d expandsbetween adjacent .endsof Athe food container and the outer container, Vand means for 'limitingtelescopic .movement of lthe food container within the outer containerwhen the food .container .is subjected to the force of the expandingexothermic material.

2. A self-heating container as `defined in claim l in which the limitingmeans includes cooperating engaging vportions carried lby vthe outeroontainer and the food container, respectively.

3. A-self-heating container as defined in claim 2 in which .the amountof exothermic :material between Ithe food container and the outerVcontainer is such that .the .cooperating ,portions lcarried .by thosecontainers will engage and limit telescopic movement of the foodcontainer while the exoithermic material still is ten-ding to-expandwhen .reacting with water.

4. A self-heating container as defined in .claim 3 in which the .outercontainer is enclosed .in a telescoping insulating casing.

5. A self-heating container as defined in=claim 3 in which the outercontainer has one end'open and the cooperating means carried thereby:for limiting telescopic movement of the food container is .positioned|adjacent the open end'thereof.

`6. A self-heating container as Ydefined in claim 5 in which thecooperating Ylimiting means carried by the food container is anoutwardly-extending projection adjacent the inner end of 'the foodContainer.

'7. A self-heating container as dened in claim 5 in which theroutwardly-eictending projection of the food container is continuous-andits outer edge lies lclosely adjacent the inner surf-aces of the sidewalls of the outer container to prevent substantial passage ofexothermic materialfwhen the exoth-ermic material is activated byreaction with water.

8. A self-heating container as defined in claim in which the cooperatinglimiting means carried by the louter container is lan inwardly-extending'flange at the open end of the sid-e walls thereof.

9. A self-heating container as deiined in claim 5 in which the`cooperating limiting means carried by the outer container is aninwardly-e tending projection adjacent and inwardly from the open end ofthe side walls thereof.

10. A self-heating container as defined in claim 5 in which means areprovided at the open end' of the louter ycontainer for making a hermeticseal with the side walls of the food container.

11. A self -heating container as deiined in claim 1 in which material ofgood heat-conductive properties extends into the body of the exothermicmaterial and is in good heat-exchange relationship with the adjacent endof the food container.

12. A self-heating containerl icomprising an outer container, a foodcontainer of heat-conductive material Within the 'outer Icontainin andtelescopically movable therein, a plurality of telescopic receptacles ofgood heat-conductive material between adjacent ends of the food`container and fthe outer container, said receptacles making a goodheat-conductive contact with the adjacent en-d of the `food container,an exothermfic material which on reaction with water liberates Iheat andexpands iwithin 'said receptacles, whereby when the exothermic materialwithin the lreceptacles is activated, th-e receptacles Will Iconductheat from said material to the adjacent end of the food receptacle.

13. A self-heating container as defined in claim 12 which includes meansfor limiting telescopic movement of the food container within the outercontainer when the food container is subjected to the force of theexpandingexothermic material.

14. A self-heating container as deiined in claim 13 in which thereceptacles generally are sector shaped.

15. A self-heating container as defined in claim 13 which hasheat-insulating means between the outer edges of the receptacles and theouter container.

16. A self-heating container as deiined in claim 13 which hasheat-insulating material between said receptacles and the adjacent endof the outer container.

17. A self-heating container as defined in claim 13 in which a layer ofthe exothermic material is between said receptacles and the adjacent endof the outer container to heat insulate the receptacles from the outercontainer.

18. A self-heating container as deiined in claim 13 in which the wallsof the receptacles nearest the adjacent end of the outer container haveopenings therein for the passage of Water to the exotherinic material.

19. A self-heating container as defined in claim 13 in which the wallsof the receptacles nearest the adjacent end of the outer receptacle haveopenings therein for the passage of water to the exothermic material,and in which portions of said walls of the receptacles adjacent theopenings are bent inwardly into the exothermic material.

20. A self -heating container as deiined in claim 13 in which the wallsof the receptacles in contact with the food receptacle are shaped toaccurately conform to the contour of the portion of 1'4 the wall of thefood container with which they are in contact.

21. A self-heating container as defined in claim 13 in which theoverlapping sides of the telescoping receptacles make a goodheat-conductive contact with one another.

22. A self-heating container as defined in claim 13 in which theoverlapping side Walls of the telescoping receptacles are of sufficientheight to remain in heat-conductive contact with one another when thefood container has telescopically moved the maximum amount permitted bysaid movement-limiting means.

23. A self -heating container as deined in claim 13 in which members ofgood heat-conductive material are embedded in theiexothermic materialand continuously maintain contact with the walls of the receptaclesnearest the food container during expansion of the exothermic materialand provide a good heat-conductive path from within the mass of theexothermic material to said walls of the receptacles. v

24. A self-heating container as defined in claim 23 in which saidmembers of good heat-conductive material are an expansible mass offlexible material.

25. A self-heating container as defined in claim 23 in which saidmembers of good heat-conductive material are springs.

26. A self-heating container as defined in claim 23 in which saidmembers of good heat-conductive material are spring members having a atcentral portion in contact with the walls of the receptacles whichcontact the food container, and radial ngers extending from said iiatcentrai portion into the mass of exothermic material.

27. A self-heating container as defined in claim 1 in which flexiblemembers of good heat-conductive material are attached to the wall of thefood container adjacent the exothermic material and extend into theexothermic material.

28. A self-heating container as deiined in claim 12 in which the end ofthe outer receptacle has means for retaining a body of water to activatethe exothermic material.

29. A self-heating container as dened in claim 28 in which thewater-retaining means comprises a gauge ring telescopically mounted onsaid end of the outer receptacle and means for limiting the outwardmovement of said gauge ring.

30. A self-heating container as defined in claim 28 in which thewater-retaining means comprises an inwardly-concaved end wall at saidend of the outer container.

31. A self -heating container as defined in claim 12 in which means areprovided for hermetically sealing the cuter container.

32. A self-heating container as defined in claim 12 in which the outerreceptacle comprises a bottom and side walls and a cover that extendsover the food container and has side walls overlapping and hermeticallysealed to the side walls of the outer receptacle.

33. A selfheating container as defined in claim 12 in which thereceptacles generally are sectorshaped and have their radial side wallsterminating short of one another at their inner ends to provide anopening into each receptacle at its apex, and a central spacecommunicates with the respective openings at the apices of thereceptacles.

34. A self -heating container as defined in claim 1 in which the end ofthe food container adjacent 15 the `exothermic material has a concaveportion extending well into said container toprovide `space `for theexothermic material.

35. A self-heating container .for frozen foods which .comprises an outercontainer, a food container of heat-conductive material within the outercontainer and telescopically movable therein, an exothermic materialwhich on reaction with Water liberates heat and expands between one .endof the food container and the corresponding end of the outer container,means for limiting telescopic movement of the food container within theouter container when the .food containeris subjected to the force ofsaid expanding ,materiaL and similar exothermic material between thefood container andthe other end of the outercontainer.. Y

`16. A self-heating container as defined in claim 35 in which theexothermic material at said other end is in a receptacle of goodheat-conductive material which has a good heat-conductive contact withsaid other end of the food container, in which the outer container is anopen-ended one having a bottom and side walls, and in which a. covermember extends over the food container and the receptacle for theexothermic material at said other end of the food container and has sideWalls overlapping the side walls of said openended outer container.

EUGENE J. RIVOCHE. LEV SUKACEV.

i6 REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number vName Date 249,769 Johnston Nov. 22, 1881794,848 Bohm July `-18, 1905 820,638 Gabriel May 115, 1906 1,751,387Bielek Mar. 18, 1930 1,955,610 Seipt Apr. 17, 1934 1,971,364 vZimmeretal Aug. 28, 41934 2,185,799 Blake retval Jan. 2, 1940 2,212,441 KatzAug. 20, 1940 2,327,447 `OBrien Aug. 24, 1943 2,425,900 Steven Aug. 19,1947 '2,553,878 vSteven May 22, 1951 'FOREIGN APATENTS Number lCountryDate 35,021 Australia Nov. 10, 1908 70,425 Australia Nov; ll), 1915V2,360 Great Britain Yof 1915 747,004 France Mar. 21,1933

